Electric-arc lamp



(No Model.) 4 Sheets-Sheet 1.

.E. THOMSON. ELECTRIC ARC LAMP.

No. 488,585. Patented Dec. 27, 1892.

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E. THOMSON. ELECTRIC ARC LAMP.

Patented Dec. 27, 1892.

(No Model.) 4.Sheets-Sheet 3.

- E. THOMSON.

ELEGTRIG ARG LAMP.-

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Patented Dec. 27 1-892.

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" (No Model.) '4 Sheets-Sheet 4.

E. THOMSON. ELECTRIC ARC LAMP.

Fmeaues: m y I 7 5 (j 1 jammy Tens 0a.. PNDTOLITHOU WASH NO ON a cIINrrE STATES 'ATENT @rrrce.

ELIHU THOMSON, OF NEW BRITAIN, CONNECTICUT, ASSIGNOR TO THETHOMSON-HOUSTON ELECTRIC COMPANY, OF BOSTON, MASSACHUSETTS.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of LettersPatent No. 488,585, dated December27, 1892.

\ Application filed'ilnly 2, 1883.

To all whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States. and aresident of New Britain, in the county of Hartford and State ofConnecticut, have invented certain new and useful Improvements inElectric Lamps, of which the following is a specification.

My invention relates to certain details of construction of electriclamps, and its object is to secure by mechanical means without the useof clock work or retarding mechanism an automatic friction,or selfregulating feed for the carbon rod.

The object of my inventionis more especially to secure ease andcertaintyof operation, and to these ends my invention consists in certainimprovements in the form of the magnet system and in the constructionand proportions of the clutch mechanism engaging with the carbon-rod orequivalent, the nature of which will be hereinafter more fully describedand will be specifically stated in the claims.

In the accompanying drawings, Figure 1. shows in elevation a lampembodying the features of my present invention. Fig 2. is a sideelevation of the same taken at right angles to Fig. 1. Figs. 3 and 4.show in detail, in side view and plan, looking upward, the form ofmagnet pole and armature that I employ. Fig 5. shows in side view thearmature and magnet pole for the main circuit magnet of a differentialelectric lamp and Fig. 6. the pole and armature of the derived circuitmagnet. Figs. 7. 8. 9. and 11. are modifications of the magnet poles.Fig. 10. is a side view of the magnet pole shown in Fig. 9. Fig. 12. isa view of the pole and armatures of Fig. 11. looking upward. Fig. 13.shows in verti cal section the form of dash pot that I prefer to employ.Fig. 14. shows in side view the clutch. Fig. 15. is a top view of thesame. Figs. 16 and 17. show in plan modified forms of clutch. Figs. 18.19. and 20. show modified dispositions of the clutch releasing stop andactuating devices therefor. v Fig. 21. illustrates the application tothe clutch of another magnet system. 7

Referring to Figs. 1 and 2. H. indicates the lamp frame or case, 0. thecap piece therefor,

Serial No. 99,764. (No model.)

and M. the usual tubular extension in which the carbon rod works, andwhich is by preference insulated on its interior surface by an enameledcoating or other insulating material to prevent electrical contact ofthe carbon rod with the tube. A plate I. hung from the cap-piece 0.supports the electro magnet of the lamp and other working parts.

D. D. indicates the direct magnet, and S. the derived circuit coils.These magnets are supported from the plate I. and their poles areconnected by a plate L of some nonmagnetic material from which issupported a lever L. pivoted at F. and carrying armatures A. A one forthe main circuit magnet and the other for the derived circuit magnet.Lever L. imparts motion through a bent spring connection K. to apeculiarly proportioned clutch C. the distinctive characteristics ofwhich will be described farther on.

J. indicates a daslrpot connected with lever L. and serving to preventor check sudden movement of the parts. The plate I. before mentioned ispreferably of iron, and serves as the connecting piece between the twocores of each magnet D. D. or S. S.

The circuits through the lamp are those usual with lamps having adifierential magnet system, and are as follows: Starting from pointX themain conductor 5. is joined to the main circuit magnet D. theotherterminal of which magnet is connected by wire 6. with a springcontact 7. bearing on the carbon carrier. through which and the carbonsE. E the current passes to point y. The derived circuit magnet S. is inthe circuit 9. taken from point I). on the main circuit wire 6. andrejoining the main circuit at point y. as usual. I have shown in Fig. 1.the magnets D. D. and S. S. as acting diiferentially on opposite sidesof the pivot F of lever L. This however, is not essential to the Workingof the other parts of my invention, as the magnets might also actindependently upon the clutch as described in other applications filedby me and as illustrated in one form in Fig. 21.

The peculiarities of the magnet system herein shown are especiallydesigned to secure long range of movement for the armature and to alsoprovide an adjustment whereby any desired variations of attractive forcein various positions of the armature may be obtained.

In Figs. 3 and 4. the pole P. of the magnet is shown as made with arounded attracting face presented to the rounded side of the armature A.and the pivot F. for the lever L. is placed so that the armature A. willswing in the path shown in dotted line, never touching the pole P. butgradually approaching said pole less and less rapidly as it nears theextreme of its upward movement, I prefer to make the outline of thearmature oval or irregular so that the magnetic effect may be varied byadjustment of the armature on or around its longitudinal axis, thusvarying the form thereof as presented to the attracting pole P. andvarying the curve of attraction as the magnet raises the armature. Forthis purpose the armature is mounted in a sleeve G in which it may beturned around its longitudinal axis, and fixed so as to present anydesired form to the pole P. by means of a set screw G. Inthedifferential system I prefer to give the pole P. of the directl'na-gnet a decreasing pull or lessened force as the armature approachesit while the pole P of the derived circuit magnet S. is given a uniformpull or attraction for the same current in all positions of thearmature. The difference in the shape of the poles by which thisdifference may be secured is illustrated in Figs. 5 and 6. The part ofthe pole P. is made flat or nearly straight at a. b. so as to be nearlyparallel with the dotted curve of the armatures swing near the extremeupward limit of its motion. While the curve of the pole P. for thederived circuit magnet and the curve of its armatures motion are suchthat the armature constantly approaches the pole as shown. From thisconstruction it results that as the lever moves under the influence ofan increased current in the derived circuit magnet; the armature of themain circuit magnet is drawn down, but owing to the peculiaritymentioned, is placed in a position Where it may exert a strongerretractive effect upon the lever. By employing a main circuit magnetthat has a decreasing pull as it moves toward the magnet, excessive orviolent movement in raising the carbon to form the arc is avoided. Otheradvantages from the combination will occur to those skilled in the artand versed in the practical operation of arc lamps. It is sufficient tosay that in practice I find this combination exceedingly effective insecuring a steady and sensitive action of the lamp, a gradual anddelicate feed of the carbons, and an avoidance of sudden movement orfluctuations in the position of the carbons with relation to oneanother.

I do not wish to be understood as limiting myself to the particular formof magnet herein described, as any magnet that is properly constructedto have a decreasing pull as the armature or equivalent part movesforward under the influence of the current in the magnetcoils, may beused in the place of thatshown and described, my invention consistingbroadly in the combination of a main circuit magnet formed orconstructed in any manner known in the artto have a decreasing pull, anda de rived circuit magnet that is suitably formed to have a uniformpull. Both poles can, however, be made like pole P provided there be arestraining spring applied so as to act in opposition to the pull of thedirect magnet pole P. as indicated at Z. This spring will, by theincreased retractive force that it acquires on being extended, make theeffect of P. in moving the armature A. a slightly decreasing one.

The oval or irregular outline given to the armatures permits of anadjustment of the balance 1;. between the magnets D. and S. when suchbalance is but approximate at first. This adjustment is secured byturning the armatures about their longitudinal axes as before described,so that they will present different exterior forms to the active surfaceor at.- tractive face of the poles. Figs. 7 and 8. show examples of thisadjustment; in Fig.7. the armature is so adjusted as to present a shortcurve to the pole, while in Fig. 8. it presents a longer-curve. Anequivalent variation of magnetic effect. for obtaining a difference ofpull between the pole and armature, as well as varied effects indilferent positions of the armature may be obtained by the arrangementshown in Figs. 9 and 10. In this case the pole P is made adjustable upona screw pin (1. so that the proximity of the poles to the armature A maybe varied as indicated by the dotted line. By giving the pole P aswinging movement on the pin d. and, when desired, a lateral play uponthe support, all desired or necessary adjustments of the parts may besecured. Such lateral play may be given by making a loose fit of the pinin the pole.

Fig. 11. shows a pole piece of proper shape for use with two armatures AA. movingin the arc of the circle around point F. and on lines indicatedby the dotted arcs. The action is the same as in the instances alreadydescribed the space between the armatures and the attracting pole facesundergoing a narrowing at a lessened rate as the armatures approach thepoles.

The general construction of the clutch is clearly shown in Figs. 1. 14.and 15. Although I have described in prior applications in general termsa clutch of the substantial construction herein shown, I purpose in thepresent instance to give to the parts certain definite proportions whichI find desirable in securing a uniform action in slowly feeding thecarbon rod, and in also attaining great delicacy of operation withregard to the force necessary to produce a feed.

In constructing aclutch having the general mechanical principle ofaction of the clutch heretofore invented by me, it is necessary in orderto obtain the best operation that the traverse or movement of the partsnecessary in order to obtain a release or feed of the carbons should beas small as possible, while at the same time in order to effect arelease with certainty and delicacy of action the mechanical forcerequired to produce such release when the clutch impinges against itsstop should also be small. These two qualities are in a measureinconsistent with one another, a small traverse of the parts to producea release, implying in this construction the exercise of considerableforce to overcome the action of the spring which holds the clutch inengagement, because a small traverse of the regulating lever toeffect'this result requires that the releasing stop should impingeagainst the arm at a point not far from the fulcrum of the jaw and ofnecessity there isa mechanical advantage in favor of the spring andagainst the effecting of a release. On the other hand if [ease ofrelease be only kept in view the traverse necessary to effect a releasebecomes so great as to destroy the efficiency. It is also desirable thatthe clamping toe while being efficient in preventing a downward movementof the carbon rod at the proper time, should as little as possible havea wedging tendency and should be capable of releasing the rod on theexercise of a very small force on the releasing arm, against the actionof the spring which holds the clamping toe against the rod. Havingregard to these various requirements I have found by actual tests andafter various experiments that the proportions and constructionshereinafter described are those well adapted to securing ease ofrelease,delicacy of action, and at the same time certainty of operation.

0 indicates the clamp body, W a clamping jaw provided with an extensionT. and pivoted in said body. S a spring that tends to hold the jaw Wengaged with the carbon rod, and B. the releasing stop which is mountedin plate L and may be set at any desired height by means of the setscrew V The spring S is secured at one end to a collar indicated at e,which may be adjusted and set in any position on the rod D. so as togive to spring S the desired initial tension. The clutch body O. is madeto encircle or partly encircle the carbon rod R. as shown and has asmall rounded bearing surface at g. Fig. 14:. upon the opposite side ofthe carbon rod from pivoted jaw or clamp W The latter is shown aspivoted upon a pin h; it is provided with a gripping surface describedupon' anarc forming a portion of a circle struck from a point X nearlyor quite vertical above the pivot h. and removed fromsaid pivotapproximately a distance equal to one-third the distance of said pivotfrom the side of the rod R. nearest it; the distance of pivot h. fromthe side of R. against which the jaw W bears is approximately one-thirdto one-quarter the distance from said pivot to the point on the extendedarm T. at which said arm comes into contact with the releasing stop B.The spring S is attached to T. as near to the stop 13. as practicable,and the elastic force of such spring as exerted upon the arm T. issubstantially one-third to one-half the weight of the rod R. togetherwith its appurtenances such as carbon clamp, and carbon. The stop B.maybe set to release the clutch at any convenient point, but suchadjustment will not disturb the adjustment of spring S since the two aremoved together. The bowed connection K. is curved so as to give it aslight elasticity and forms an improved elastic connection which hasbroadly been made the subject of prior application filed by me.

In Figs. 16. and 17'. the form of the rod R. is slightly different; inFig. 16. it is angularand the body 0. is provided with a correspondingangular bearing recess. In Fig. 17, the general form of the rod issquare.

The dash pot that I prefer to use is shown in Fig. 13. and consists ofclosed case J. closed at its top, in the interior of which is a longpiston J made hollow for lightness. The connecting head W. of the pistonrod which is connected with lever L. Fig.1. is made to close the end ofthe case J. as a valve at W when the dash pot piston J is in its upperposition in the case when the lamp is out of use, thuseffectuallyexcluding dust from the interior of case J. The neck of the case J. isopen only when in use and its upper end being shut no dust is liable toenter.

Several mechanical equivalents of the clutch are shown in Figs. 18. 19.and 20. In Fig. 18. the arm T. is shortened, and the spring S isconnected to a downwardly projecting arm through which it may beattached at any desired point, in such way as to produce upon the arm T.the same mechanical effect as the spring of Fig. 13, applied to give therelative force above defined. The shortening of the arm T. iscompensated for by making the stop B. movable upward by lever L. andlink connection so as to exert a lifting force upon T. as K. descends.K. maybe also brought nearer to the fulcrum F. for the same purpose. Theparts are so proportioned that the lever L. is called upon to exert thesame force in relieving the clutch as it does in Fig. 13. so that ineither case a given variation of the magnet.

strength will actuate the mechanism. In Fig. 19. the arm T. islengthened and the stop B. made movable upward as K. descends but at arate determined by the mechanical effect to be produced, so that theforce exerted by the lever L. in releasing the clutch will be the sameas in the preceding cases. In Fig. 20. the parts are a littledifferently arranged, but the same proportions to produce the samemechanical effects are to be observed.

Theoperation of the lamp Fig. 1. is as usual. On passage of current thearmature A. is attracted closing the clutch O. and forming an arc, butits movement is restrained by the armatures A acted upon by the pole ofthe derived circuit magnet. When the arc is lengthened by consumption ofthe carbons, the armature A. overcomes armature A. and

lowers the clutch till the arm T. comes against the stop 13. when byvirtue of the proportions of parts asset forth a slow slip or feed takesplace and is maintained. An effective and practical feed may be producedby the arrangements herein described without resort in g to clock workmechanism, or dash pot retarding devices attached to the carbon carrieror geared with it. I believe that I am the first to effect such aresult.

My invention is not confined to what is known as the diiferential magnetsystem, and may be applied through a magnet system such as shown in Fig.21. and as is substantially shown in other applications forpatents filedby me. In this case the direct magnet D. is an ordinary magnet acting toraise one end of a bar L. with which the spring lifting arm K. isconnected, its action in this particular taking place without anymovement on the part of the armature for the derived circuit magnet S.whose armature is connected to the opposite end of the bar L The clutchO. is thus lifted so as to form the arc and is held in such positionuntil the are lengthens, when the derived circuit magnet moves itsarmature against the action of a spring Z. and lowers the end of L towhich itis pivoted, so as to lower the clamp and cause a feed of thecarrier to take place. This action takes place independently of themagnet D. whose armature remains attracted after it has been drawn downso as to form the are. No claim is made herein to such combination ofindependently acting magnets, as it forms the subject of anotherapplication for patent already filed by me.

WVhat I claim as my invention is:

1. The combination in an electric lamp, of a derived circuit magnet anda main circuit magnet pulling, against one another on the sameregulating lever said derived circuit magnet havinga uniform magneticpower for the same strength of current in all positions of its partswhilethe magnetic power of the main circuit magnet decreases as thearmature approaches the end of its movement under the influence of thecurrent in the said magnet coils, as and for the purpose described.

2. The combination in a dilferential lamp, of a main circuit magnetWhose pole piece has an attracting face curved as described, so thatnear the extremity of its armatures movement it will cease to approachthe pole, and a derived circuit magnet having a curved attracting poleand armature swingingpast the face thereof, the curve of the attractingface being made in the manner desired so that the armature shallgradually approach the pole through its whole range of movement, as andfor the purpose described.

The combination with the feed controlling devices in an electric lamp,of a governing electro magnet having curved attracting pole, and anarmature therefor arranged to swing in a curved path whose generaldirection is parallel to that of the attracting pole face, said armaturebeing adjustable about an axis parallel with the attracting pole facebut transverse to the path described by the armature whereby its formand mass as presented to the pole may be varied.

4. The combination with the carbon carrier foran electriclamp, of aclamp body surroundin g the carrier, a pivoted clam ping jaw pivoted onsaid body, and a clamp face or surface on the jaw curved on an arc of acircle drawn from a center nearly or quite vertical above the pivotalpoint of the jaw.

5. The combination with the carbon carrier,

of a pivoted clamp jaw having a clamping.

surface curved on the arc of acircle described from a point verticallyabove the pivotal point, and removed therefrom approximately one thirdof the distance of said pivotal point from the side of the carboncarrier.

6. The combination with the clamp and its operating armature of theintermediate elastic bowed connecting piece K, as and for the purposedescribed.

7. The combination with the carbon adj usting mechanism of the invertedair dash pot. cylinder connected therewith, a fixed or stationary pistonand rod, and a valve upon the piston rod and exterior to the cylinderfor preventing ingress of dust when the lamp is out of action.

8. In an electric arc lamp, a pivoted clam ping jaw havingacurved bitingsurface curved on the arc of a circle described from a center above thepivotal point of the jaw. and having a radius less than the distance ofthe pivot from the surface with which the jaw engages.

Signed at New Britain, in the connty of Hartford and State ofConnecticut, this 29th day of June, A. D. 1883.

ELIHU THOMSON. Witnesses:

W. O. WAKEFIELD, JAMES F. MnEoH.

